Errors in the angular power spectrum, derived as the square root of diagonal elements of Cov_ℓℓ′, in real (blue squares), redshift (with σ_z = 0, black circles) and in photo-z space, with σ_z = 0.02, (red triangles) and σ_z = 0.05 (green triangles), from the numerical covariance matrix measured from 1000 mocks. The lines show the results obtained with the linear power spectrum in the Limber approximation (solid black line), with the exact integration given by Eq. (43), which also includes the modelling of the RSDs (dashed red line) and with the damped linear power spectrum in the Limber approximation (solid red and green lines).